This disclosure relates to surgical instruments, and in particular to surgical cutting instruments having mechanical cutting blades and one or more electrodes for providing surgical energy to the treatment area (e.g., for coagulation, vaporization of tissue, and/or other treatment effects).
Surgical apparatus used to shave, cut, resect, abrade and/or remove tissue, bone and/or other bodily materials are known. Such surgical apparatus can include a cutting surface, such as a rotating blade disposed on an elongated inner tube that is rotated within an elongated outer tube having a cutting window. The inner and outer tubes together form a surgical cutting instrument or unit. In general, the elongated outer tube includes a distal end defining an opening or cutting window disposed at a side of the distal end of the outer tube. The cutting window of the outer tube exposes the cutting surface of the inner tube (typically located at a side of the distal end of the inner tube) to tissue, bone and/or any other bodily materials to be removed. A powered handpiece is used to rotate the inner tube with respect to the outer tube while an outer tube hub (connected to the proximal end of the outer tube) is fixed to the handpiece and an inner tube hub (connected to the proximal end of the inner tube) is loosely held by the powered handpiece and is rotated by a motor of the handpiece.
In some instruments, the inner tube is hollow and has a cutting window on a side surface near its distal end such that tissue, bone, etc., will be cut or shaved as the cutting window of the inner tube aligns with and then becomes misaligned with the cutting window of the outer tube as the inner tube is rotated within the outer tube. In this regard, it can be said that the cutting device nibbles or takes away small pieces of the bone, tissue, etc., as the inner tube is rotated within the outer tube.
In some instruments, a vacuum is applied through the inner tube such that the bodily material that is to be cut, shaved, etc., is drawn into the windows of the inner and outer tubes when those windows become aligned, thereby facilitating the cutting, shaving, etc., of the tissue, which then travels through the inner tube due to the suction. It also is common to supply an irrigation fluid, which can include a liquid, to the surgical site via a passage provided between the inner and outer tubes.
Microdebrider shaver blades are common instruments used in endoscopic surgery. The shaver blade delivers high speed mechanical cutting of tissue at a specified area of anatomy that the surgeon can reach through a minimally invasive incision or natural orifice. One challenge during procedures using such instruments can be the slowing down or stopping of bleeding (hemostasis) during the procedure. One solution for maintaining proper hemostasis during a procedure is to utilize an electrocautery instrument that can be used inside the same minimally invasive surgical corridor. In a minimally invasive procedure, every time the surgeon exchanges the cutting instrument for the electrocautery instrument there is a corresponding increase in the time required to perform the procedure and there is a risk of traumatizing the anatomy due to the exchange of the instruments. Thus, it is convenient to combine the mechanical cutting and electrocautery instruments to form one instrument performing both functions. By providing a microdebrider shaver blade that also can perform electrocautery, the need to perform tool exchanges at the surgical site is reduced and can even be eliminated.
There are two standard types of electrocautery: bipolar and monopolar. Monopolar cautery uses one electrode at the surgical site and then relies on a neutral electrode placed somewhere else on the patient (typically on the skin of the patient) to help disburse the energy enough to pass the energy safely through the patient. Bipolar cautery does not use a separate neutral electrode. Instead, bipolar cautery delivers the energy and returns the energy through the device using two electrodes at the surgical site. That is, a bipolar device will provide two electrodes at the surgical site, one active electrode and one return electrode.
It is known to provide microdebrider shaver blades with bipolar energy electrodes to perform the electrocautery. As is known, cutting or shaving takes place by rotating (or oscillating with some devices) the inner cutting blade while suction is applied through the device. An electrical signal appropriate for achieving electrocautery is applied to the active electrode so that tissue is cauterized to achieve hemostasis during use of the device.
It also is known to perform surgical cutting using only electrical energy. For example, a cutting device such as an electrical scalpel can be used to completely remove the surgical area. Such devices are used, for example, to perform tonsillectomies. These electro-surgical devices generally have no moving parts to engage the tissue. Thus, these procedures in which electrical energy is used to remove tissue are often performed “open” and make use of manual grasping instruments to bring the tissue into contact with the cutting electrode.